Method of making tire stud

ABSTRACT

A TIRE STUD AND THE METHOD OF MAKING SAME. THE TIRE STUD INCLUDES AN ELONGATED METAL BODY HAVING A HEAT AT ONE END AND A SHANK EXTENDING FROM THE HEAD WITH A CAVITY EXTENDING INTO THE SHANK TOWARD THE HEAD. IN MAKING THE COMPLETED STUD, THE BODY IS DISPOSED IN A BORE HAVING A SHANK RECEIVING PORTION AND A SMALLER PROTION WHICH IS GENERALLY OF THE SAME CROSS SECTIONAL AREA AS THE CAVITY AND WHICH EXTENDS UPWARDLY FROM THE CAVITY TO AN OPENING. MATERIAL IS DISPOSED THROUGH THE OPENING TO FILL THE CAVITY AND AT LEAST A PART OF THE SMALLER PORTION OF THE BORE ABOVE THE CAVITY. THESE MATERIALS INCLUDE PARTICLES MADE OF CARBON GRAINS SINTERED TOGETHER BY A BINDER SUCH AS COBALT AND AN ADDITIONAL FILLER METAL POWDER. THE FILLER METAL POWDER IS MELTED SO AS TO FILL THE SPACES BETWEEN THE PARTICLES AND THEREAFTER SOLIDIFIES TO FORM A COMPOSITE OF THE PARTICLES BONDED TOGETHER BY THE FILLER MATERIAL.

g- 197 c. s. BAUM METHDD OF MAKING TIRE STUD Original Filed May 15, 1970METHOD OF MAKING TIRE STUD Charles S. Baum, St. Clair Shores, Mich.,assignor to "Textron Inc.; Providence, RI.

Original application May 15, 1970, Ser. No. 37,708. .Divided and. thisapplication May 17, 1973, Ser. No.

Int. Cl. B22f /00 US. Cl. 75 ,208 R a 8 Claims ABSTRACT OF THEDISCLOSURE A tir e'stud and thelmethod of making same. The tire studincludes an elongated metal body having a head at one end and a shankextending from the head with a cavity extending into the shank towardthe head. In making the completed stud, the body is disposed in a borehaving a shank receiving portion and a smaller portion which isgenerally of thesame cross sectional area as the cavity and whichextends upwardly from the cavity to an opening. Material is disposedthrough the opening to fill the cavity and at least a part. of thesmaller portion of the bore above the cavity. These materials includeparticles made of carbon grains sintered together by a binder such ascobalt and an additional filler metal powder, The filler metal powder ismelted so as to fill the spacesbetween the particles and thereaftersolidifies to form a composite of the particles bonded together by thefiller material.

This application is a divisional of my earlier filed copendingapplication Ser. No. 37,708, filed May 15, 1970.

This invention relates to a stud for pneumatic snow tires, the studbeing imbedded in the rubber or other elastomeric material of the tireto provide increased traction.

As is well known, that portion of the stud which is to engagethe'ro'adway must be of very tough, wear-resistant material. By'far, themost commercially successful tire stud -is-of the'type comprising anelongated metal body with a head on'one end and a bore extending intothe body with a sintered tungsten carbide insert secured in the "boreand extending therefrom for engaging the pavement'. UntilnoW, thoseskilled in the art believed that carbidessuch as sintered tungstencarbide formed into an insertbody were the only practical materials touse to obtain 'tlierequisite wear characteristics. An example of suli'"a stud 'is'shown in US. Pat. 3,125,147.

S tered tungsten carbide comprises individual grains of a'rb'ide boundtogether by a binding metal such as cobalt. Other binding materials maybe utilized but cobalt is preferred and is mostyvidely used becausecobalt dissolves only about one percent ofthe tungsten carbide and has asuperior'ability to wet the carbide at elevated temperatures as duringsintering.

Sintered tungsten carbide is frequently manufactured. by placing atungsten carbide powder with a cobalt powder in aybal l mill forcrushing and thereafter screening"; the crushed mixture and pressingthis mixture into a form. Thereafter, the form is sintered by placing itin a furnace or-ioveniand elevated. to a temperature that melts thecobaltaBy comparison, a .tire stud made in accordance with the instantinvention is much less expensive. g p

One of the'operational problems associated with the present tire studswhich have a metal bodywith the tungsten carbide extending therefrom, isthat the wear of the tungsten carbide is not commensurate with the wearof the metal body and the tire. The metal body surround-. ing thetungsten carbide wears rapidly compared to the tungsten carbide, as doesthe tire. Frequently, the elongated length of tungsten carbide issharpened during wear and is forced back into the tire to puncture thetire. In

3,82 7,885 Patented Aug. 6, 1,974

other words, one of the problems with the present tire studs utilizingtungsten carbide is that the tungstencarbide is too wear resistant.

Accordingly, it is an object and feature of this invention to provide animproved tire stud used to overcome the economic and operationaldisadvantages of the prior art tire studs.

In correlation with the foregoing object and feature, 3 it is anotherobject and feature of this invention to pro-. 1 vide an improved tirestud which utilizes presently used carbide but is in a different formwhich is more economical to manufacture and which provides the desiredwear characteristics.

In correlation with the foregoing objects and features,

it is another object and feature of this invention to provide a tirestud employing particles made up of grains of carbide sintered togetherby a binder metal with the particles in turn being bonded together by afiller metal,

In correlation with the foregoing objects and features, it is anotherobject and feature of this invention to provide a tire stud employingparticles made up of grains of tungsten carbide sintered together withcobalt as a :1; binder with these particles in turn being bondedtogether by copper or nickel. 1

Other objects and attendant advantages of the present invention will bereadily appreciated asthe same becomes j better understood by referenceto the following detailed description when considered in connection withaccompanying drawings wherein:

FIG. 1 is a fragmentary cross sectional view showing a preferredembodiment of a tire stud manufactured in accordance with the instantinvention;

FIG. 2 is an enlarged view of the materials shown in the circleindicated in FIG. 1; FIG. 3 is a plan view of a mold which invention;and

FIG. 4 is a cross sectional view taken substantially along line 4-4 ofFIG. 3.

Referring now to the drawings wherein like numerals shank portion iscircular. Thebody 12- is madeof a metal such as steel. 7

A composite body, generally indicated at 20, ,is disposed and retainedin thecavity 18 and extends from-the cavity and the body 12. l

The composite body 20 includes.particles=;22 made up .:.of carbon grains2.4 sintered'together with a bindermetal 26. The particles 22are.bound-togetherby a filler metal- 28 surrounding and fillingthespaces between and-a bind ing together the particles 22. Morespecifically, the particles, comprisev tungsten-car cobalt is thebinder. metal. The filler -metal 28 is .at;. least in part, i.e..analloy, of the metal from the group coma prising copper and; nickel. Inother words,.the filler metal is either copper or nickel or'v an.alloyithereof.

may be utilized. 5 in manufacturing tire studs in accordance with theinstant .bide .grains 24 sintered together with cobalt: 26, i.e.-,the,,

1f Thereisa plentiful ,supplyof discarded. carbidefparts:

As an example, tungsten carbide cuttingqinse'rts are .disposed inmilling head cutting wheels and. after; sufficient comprise tungstencarbide grains sintered together with a binder metal such as cobalt. Inaccordance with the instant invention these discarded parts are crushedto obtain particles which will compn'ses tungsten carbide grainssintered together by cobalt.

These particles are utilized in the instant invention by utilizing amold such as that shown in FIGS. 3 and 4. The mold shown in FIGS. 3 and4 includes a plurality of bores 30. Each bore 30 has a shank receivingportion 32 for receiving the shank 16 of the metal body 12. Each borealso includes a smaller portion 34 which is generally of the same crosssectional area or diameter as the cavity 18 and extends upwardly fromthe cavity 18 to a tapered opening 36.

In accordance with the instant invention, scrap parts are crushed to thedesired particle size and the particles are disposed through the opening36 to fill the cavity 32 in the metal member 12. Also inserted throughthe opening 36 is a powdered filler metal such as copper. The powderedmetal and the particles may be pre-mixed before disposition into thebores or the particles may be inserted first with the metal powderassociated therewith by being disposed in a layer thereabove. In anycase, the total combination fills the cavity 18 in the shank 16 and atleast a length of the smaller portion 34 of the bore. Once this isaccomplished the entire mold is placed in a furnace or oven and raisedto a temperature for melting the powdered metal so that the filler metal28 flows about particles 22 to fill the spaces therebetween. Thecomposite is allowed to solidify by cooling whereby the particles 22 arebonded together by the filler material 28. The filler metal also adheresto the metal body to retain the composite in the cavity 18.

The tire stud constructed in accordance with this invention whenoperatively associated with a tire, provides improved characteristics inthat the composite insert wears commensurately with the wear of thepedal body 12 and therefore overcomes the problems associated with theprior art tire stud. The reason for the wear of the composite 20 beingmore commensurate with the wear of the metal body 12 is that theparticles 22 provide all of the wear resistant characteristics known topreviously utilized solid sintered tungsten carbide, yet the fillermetal such as the copper or nickel ueagtes to some degree such wearingcharacteristics so that the insert, albeit providing the requisite wearcharacteristics, is not so tough in wear resistance that problems arecreated.

It will be appreciated that since the basic tungsten carbide materialmay be purchased as scrap and merely crushed to the desired particlesize, that tire studs constructed in accordance with the instantinvention are much less expensive than tire studs using a solid insertof sintered tungsten carbide yet provides the requisite wearcharacteristics without being so tough so as to create problemsassociated with the prior art tire studs.

The mold may be subjected to a temperature of approximately 1800 to 2400degrees F. to effect the melting of the' filler material. When thetiller material is copper it is preferably heated 'to a temperaturesuflicient for the copper "to thoroughly wet the particles 22. Coppermelts at about 1850 F. but it is preferably heated at least to a brazingtemperature of 2050 P. so that a metalluragical bond occurs between thecopper and the particles as the filler metal infiltrates the particles.

The invention has been described in an illustrative'man ner, and it isto'be understood that the terminology which has been used isintended tobe in the natureof words of description rather than of limitation. I p,Obviously, many modificationsa'nd variations'of the present inventionare possible in'light of the above tea'ch-" ings.' "It is; therefore tobe understood that within the scope of the appended claims, theinvention may be prac ticed otherwise than as specifically described.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows: 1. A method of making anarticle suitable for use as a tire stud of the type including abody,having ahead and a shank with the extremity opposite the head made bythe steps of: disposing carbide grains sintered together by a metalpowder within a cavity vin=the shank-rand raising the temperature of themetal powder so that thefiller metal bonds the particles together."- 5

2. A method of making an article suitable for use a tire stud of thetype including a metal body having a head at one end and a cavityextending thereinto from the opposite end, said methodcomprising thesteps of binder metal to form particles in association :with a filler.-

disposing particles madeoff carbide grains sintered together by a bindermetal in said'cavity, disposing a filler metal powder in associationwith said particle's,'and i-ais- 1 ing the temperature of themetalfpowder'so thatthe metal flows about the particles to fillthe"spaces thereb e-' tween and allowing the filler metal to solidify toform a composite of the particles bonded together by the filler] metal.

3. A method as set forth in claim 2 wherein said afar:

ticles comprise sintered tungsten carbide.

4. A method as set forth in claim 2 wherein saidjparticles comprisetungsten carbide grains sintered together j with cobalt as said bindermetal.

5. A method as set forth in claim 2 wherein said filler metal is atleast in part of a metal group comprising" copper and nickel.

6. A method as set forth in claim 5 wherein said par- 1 ticles comprisetungsten carbide grains sintered together with cobalt as said bindermetal.

7. A method as set forth in claim 2 including packing said carbideparticles into said cavity.

8. A method for making a tire stud of the type includ,-

and a shank extending from the head with aycavity extending into theshank toward the head, said method com-, prising the steps of: disposingthe body in a bore having 1 ing an elongated metal body having a head-atone end a shank receiving portion and a smaller portion which isgenerally of the same cross sectional area as the cavity and extendsupwardly therefrom to an opening, disposing materials through saidopening to fill said cavity and at least part of said smaller portion ofsaid bore, said materials comprising carbide grains sintered together bya binder metal to form particles and a filler metal powder, and raisingthe temperature of the tiller metal powder-s0 that the filler metalflows about the particles 'to fill the CARL D. QUARFORTH, PrimaryExaminer B. HUNT, Assistant Examiner v U.S. Cl.'X.R.

